Abrasive tester



Jan. 18, 1966 E. w. OAKES 3,229,498

ABRASIVE TESTER Original Filed May 10, 1962 36 I A, H a I Edward W OQAQJ INVENTGR.

United States Patent 3,229,498 ABRASIVE TESTER Edward W. Oakes, Houston, Tex., assignor to Clemtex, Ltd., Houston, T ex., a partnership of Texas Continuation of application Ser. No. 193,720, May 10, 1962. This application Feb. 16, 1965, Ser. No. 433,085 1 Claim. (Cl. 737) This invention pertains generally to testing apparatus and methods and particularly to apparatus and methods utilized in testing various qualities of abrasive materials. This application is a continuation of my copending application filed May 10, 1962 under Serial No. 193,720 and entitled Abrasive Tester, now abandoned.

During the past few years, people working in the corrosion prevention and protection industry have designed various protective coating films of excellent quality and durability when they are applied over properly prepared surfaces. However, because film thicknesses and adhesion requirements are critical, even more stress has been placed on proper foundation work during surface preparation. Blasting with proper abrasive media has provided proper surface preparation in an economical and efficient manner.

The blasting of surfaces in preparing for applying coating films is a relatively simple procedure wherein only two end components are involved. These components are the abrasive material and its velocity. However, these two components are subject to many variables and therefore a relatively simple method may become quite complex. With a properly standardized procedure of identifying all available abrasives for use in surface preparation, corrosion engineers and others can readily ascertain the requirements of a particular abrasive material in order to obtain proper surface preparation results in a particular geographical area. Readily available abrasives such as silica vary according to the geographical location from which they are obtained. Thus, the present invention is concerned with the apparatus and methods of testing abrasive materials whereby such abrasive materials may be classified according to the physical properties of break-down and abrading characteristics. Prior to the present invention, no standardized methods or ap paratus were available to readily ascertain the breakdown and abrading characteristics of abrasive materials. Although the Mohs test has been used to a limited extent, the Mohs test of hardness has not provided the neces sary information supplied by the present invention.

Thus, it is an object of the present invention to provide an improved testing technique.

Another object of the present invention is to provide apparatus and methods for testing abrasive materials regardless of Whether such abrasive materials are synthetics, silica, or natural minerals.

Still a further object of the present invention is to provide apparatus and methods for determining in a simple and efiicient manner the break-down and abrading characteristics of abrasive materials.

A still further object of the present invention is to provide apparatus and methods of testing various abrasive materials so that comparison tables may be prepared showing the break-down and abrading characteristics of such abrasive materials.

In the drawings, FIGURE 1 is an elevational view of the equipment utilized in the present invention;

FIGURE 2 is a cross-sectional elevational view of the housing utilized in the present invention and shown in FIGURE 1;

FIGURE 3 is a test specimen showing a typical testing pattern caused by abrasive blasts;

FIGURE 4 is a perspective view of the receptacle for a test specimen.

3,229,498 Patented Jan. 18, 1966 Briefly stated, the invention incorporates apparatus and methods for determining break-down (hardness) and abrading characteristics of abrasive materials. The apparatus comprises a housing having disposed therein a nozzle conduit and a nozzle fixed at a definite angular relationship within the housing. Also disposed in the housing is a test specimen receptacle pivotally mounted so that the test specimen may be positioned at an angle of 45 degrees to the test nozzle or may be perpendicular to the blast from such test nozzle. Means are provided for discharging the abrasive materials to be tested at a preselected velocity. Means are also provided for collecting dust which may accumulate inside the housing. A fixed volume of abrasive material to be tested is discharged through a nozzle in the housing with the discharge being directed against a test specimen. The change in particle size of the abrasive sample being tested is noted and the decrease in thickness of the test specimen is also noted. The change in particle size of the sample abrasive material and the decrease in thickness of the test specimen may be correlated and tabulated to indicate relative hardness and abrading ability of the various types of abrasive samples which have been tested.

Referring now to the drawing in detail, FIGURE 1 shows a conventional container 10 having an air inlet 12. Abrasive test samples to be tested are placed in container 10 and a suitable air supply line is coupled to inlet 12. Part of the air supply is fed through conduit 13 directly to outlet 14. Thus an air and abrasive combination is discharged through conduit 16 and through a nozzle in "ice housing 20. The interior of housing 20 will be described in more detail subsequently.

Housing 20 may be comprised of four vertical members positioned on legs such as legs 22 and 24 which are the only legs visible in FIGURE 1. Housing 20 has a top 26 wherein an aperture 28 is disposed. A suitable conduit 30 is coupled to aperture 28 and to aperture 32 in dust collector device 34.

Housing 20 includes a door 36 positioned on hinges 38 and 40. Door 36 allows access to the inside of housing 20 so that test specimens may be inserted and removed in a manner to be explained subsequently. A portion of the test receptacle is visible in FIGURE 1 as member 42 protrudes from housing 20.

The lower portion of housing 20 is a cone shaped section 44 wherein the abrasive material being tested is deposited prior to emptying into container 46 immediately below the housing 20.

FIGURE 2 is a cross-sectional elevational view of housing 20 showing vertical members 21 and 23 coupled to the top 26. Top 26 has duct 30 coupled thereto at aperture 28. Two baflles 50 and 52 are positioned in the housing 20 as shown. Baflies 50 and 52 are positioned so as to retain blasted abrasives within the housing 20. The area in back of the test specimen receptacle and below the lower battle 52 is lined with rubber 53 to prevent secondary abrasive break-down after initial contact with metal test specimen.

A test specimen receptacle 54 is pivotally coupled to vertical member 23 through a hinge 56. Thus, test specimen receptacle 54 may be rotated so that the test specimen 58 is perpendicular to the discharge from nozzle 19 or the test specimen 58 may be positioned against vertical member 23 so that the discharge from nozzle 19 makes a 45 degree angle with the test specimen 58. Member 42 passes through aperture 66 in vertical member 23 to allow the position of the test specimen 58 to be changed without opening the door 36 to the housing 20. Member 42 is retained in a fixed position by fastening means 62 which may be a set screw. When the test specimen 58 is positioned against vertical member 23, the nozzle 19 is moved so that a distance of 6 inches is maintained between the end of nozzle 19 and the test specimen 58. Thus, a fixed distance is maintained between the test specimen 58 and nozzle 19 regardless of the angular position of such test specimen.

FIGURE 3 is an elevational view of test specimen 58 showing a wear pattern 64. Wear patterns will vary with different types of abrasives.

FIGURE 4 is a perspective detail view of the test specimen receptacle 54 showing a test specimen 58 positioned therein. The test specimen receptacle 54 may include channel members 66 and 68 which are coupled to a substantially flat back member 70. Thus the test specimen 58 may be slidably inserted and removed in the receptacle. Fastening means such as a set screw 72 may be positioned in channel 68 to retain the test specimen 58 in the receptacle 54. V Member 42 is coupled to the back plate 70 in a suitable pivotal manner. The operation of the apparatus will now be explained.

The test procedure is performed in two phases. The first phase is a break-down or hardness test and the second phase is an abrading test. In the break-down test a sample of abrasive material to be tested is screened to the following specifications:

Percent Retained on US. Sieve No. 20 Retained on U.S. Sieve No. 30 100 The abrasive material sample is then blasted at 90 9 lbs. per square inch nozzle pressure until all of the sample is expended. An adequate capacity air transformer may be necessary to maintain proper nozzle pressure. Also, a moisture control trap should be installed in the system. The spent sample is then rescreened on the US, Sieve No. 30 and the remaining sample is weighed and recorded in order to calculate a percentage break-down from the original sample tested.

Example Weight of material between No. 20 x 30 Sieve: Pounds Before test 12.25

After test 1.50

Wgt. Before Test-Wgt. After Test Wgt. Before Test 12.25 lbs. 1.50 lbs.

12.25 lbS.

Break-down= =88% of original sample Therefore the break-down or hardness number is equal 100 minus 88 and that is equal to 12 which is a substantially low hardness inasmuch as hardness numbers range from 0 to 100.

The abrading test procedure will now be described. The abrading test is performed using a similar prescreened 20 x 30 mesh sieve sample of /s cubic foot volume of abrasive material to be tested. The sample is blasted through the pressure blast machine as described in the break-down test while again using a 7 round orifice having a 4" length with boron carbide lining. Whereas the test specimen was perpendicular to the nozzle outlet in the breakdown test, the present test procedure uses the test specimen at a 45 degree angle from the line of abrasive blast. As in the break-down test 90 lbs. per square inch nozzle pressure is utilized.

The test specimen is a 7 thick A-7 steel 3" x rectangular sample which is measured with a micrometer in the general area of expected blast pattern prior to test. After the abrasive material sample has been expended the metal sample is again measured with a micrometer and the difference provides the amount of metal removed from the test specimen.

Abrading N0.=64.5.The abrading number is the depth of metal removed multiplied by 1000. Thus the abrading number may range from 0 to 187.5.

The amount by volume of the sample abrasive material was determined as /s cubic foot so that all of the available abrasives could be used and evaluated with a thick steel sample plate. The size of abrasives by US. Sieve screens was determined because of maximum use of abrasizes in these sizes are recommended for surface preparation. Abrasives cannot be screened to the sizes utilized in the testing procedure for industrial use because of economical limits. However, a common size of 16 mesh by 40 mesh with 10% tolerances can be specified and obtained at economical cost while still maintaining quality results during industrial uses. The simple formula of air pressure (velocity) times abrasive weight equaling impact requires the pressure during the test to be maintained at an absolute constant.

Thus, applicant has provided a new and useful apparatus and methods for testing abrasives lELS to hardness and abrading ability. Such apparatus and methods utilize only one variable and that is the type of abrasive sample being tested. Therefore, an accurate tabulation of results of various test samples may be ascertained and useful information is compiled. The apparatus and methods of the present invention fill a long felt need for a testing procedure of this type.

Although a preferred embodiment of the invention has been shown and described, it is to be understood that the invention is defined by the following claim. Although the claim may be presented in indented format to facilitate reading and understanding thereof, such indented format is not to be construed as being a structural or functional limitation of the claim.

I claim:

A housing adapted for use with abrasive testing apparatus, said housing including a plurality of vertical members converging into a cone at the lower portion of the housing,

a cover engaging each of said plurality of vertical members at the upper portion of the housing, a door hinged to one of said vertical member's thereby allowing access to the interior of the housing,

first and second baflle members disposed in the housing each of said members being at an angle of 45 degrees with the vertical and perpendicular to each other,

an aperture in the lower part of the housing adapted for receiving a nozzle conduit, and

a pivotal receptacle adapted for receiving a test specimen, said receptacle being positioned opposite said aperture whereby said receptacle may be perpendicular to the line of discharge from the nozzle conduit or at a 45 degree angle thereto.

References Cited by the Examiner UNITED STATES PATENTS 1,444,803 2/ 1923 Ratner et al. 737 1,446,977 2/1923 Vercombe 737 2,016,779 10/1935 Hardgrove 737 2,093,650 9/1937 Sunnen 737 2,907,200 10/1959 Roberts et al 73--7 DAVID SCHONBERG, Acting Primary Examiner.

LOUIS R. PRINCE, Examiner. 

